U.S. Pat. No. 5,307,962 issued to the same inventor of this application disclosed a container mounted pump with an improved check valve formed thereon. However, the spring (3), provided for urging the piston (2) upwardly when releasing the nozzle head (1) to suck liquid into the accumulator (4) for pumping liquid outwardly, is formed in the accumulator (4) to be impregnate ed in the liquid to possibly contaminate the liquid by the spring. The spring (3), if being made of steel or iron material, may be Corroded or eroded by the liquid (aqueous solution) within the accumulator.
The present inventor has found the drawbacks of the conventional a container-mounted pump and invented the present pump means having external restoring spring provided outside the accumulate or.